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 A237929 Numbers n such that (i) the sum of prime divisors of n (with repetition) is one less than the sum of prime divisors (with repetition) of n+1, and (ii) n and n+1 have the same number of prime divisors (with repetition). 2
 2, 9, 98, 170, 1274, 4233, 4345, 7105, 7625, 14905, 21385, 30457, 34945, 66585, 69874, 77314, 82946, 98841, 175354, 177122, 233090, 236282, 238017, 263145, 265225, 295274, 298082, 322234, 335793, 336106 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The first term a(1)=2 is the only prime number in this sequence. LINKS Abhiram R Devesh, Table of n, a(n) for n = 1..96049 EXAMPLE For n=98: prime factors = 2,7,7; sum of prime factors = 16; number of prime divisors = 3 For n+1=99: prime factors = 3,3,11; sum of prime factors = 17; number of prime divisors=3. PROG (Python) ## sumdivisors(n) is a function that would return the sum of prime ## divisors of n ## numdivisors(n) is a function that would return the number of prime ## divisors of n i=2 while i < 100000: ..sdi=sumdivisors(i) ..sdip=sumdivisors(i+1) ..ndi=numdivisors(i) ..ndip=numdivisors(i+1) ..if sdi==sdip-1 and ndi==ndip: ....print i, i+1 ..i=i+1 CROSSREFS Cf. A001414, A006145 Ruth-Aaron numbers (1): sum of prime divisors of n = sum of prime divisors of n+1. Cf. A228126 Sum of prime divisors of n (with repetition) is one less than the sum of prime divisors (with repetition) of n+1. Cf. A045920 Numbers n such that factorizations of n and n+1 have same number of primes (including multiplicities). Sequence in context: A013132 A317275 A013057 * A227258 A027686 A360696 Adjacent sequences: A237926 A237927 A237928 * A237930 A237931 A237932 KEYWORD nonn AUTHOR Abhiram R Devesh, Feb 16 2014 STATUS approved

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Last modified March 30 09:39 EDT 2023. Contains 361609 sequences. (Running on oeis4.)